Pulsed electronic article surveillance detection system absent of a phasing requirement

ABSTRACT

Systems and methods for detecting a marker in a pulsed Electronic Article Surveillance (“EAS”) system. The methods comprise transmitting, from an EAS detection system, an excitation signal having a first frequency into an interrogation zone during a transmit phase of the EAS detection system. The excitation signal causes the marker to transmit a response signal having a second frequency different from the first frequency. The response signal is received at the EAS detection system during a receive phase of the EAS detection system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of U.S. Provisional Ser. No.62/371,073 filed Aug. 4, 2016, which is incorporated in its entirety byreference herein.

BACKGROUND Statement of the Technical Field

The present disclosure concerns generally to Electronic ArticleSurveillance (“EAS”) detection systems. More particularly, the presentinvention relates to EAS detection systems absent of a phasingrequirement.

Description of the Related Art

A typical EAS system in a retail setting may comprise a monitoringsystem and at least one marker (e.g., a security tag or label) attachedto an article to be protected from unauthorized removal. The monitoringsystem establishes a surveillance zone in which the presence of markerscan be detected. The surveillance zone is usually established at anaccess point for the controlled area (e.g., adjacent to a retail storeentrance and/or exit). If an article is authorized for removal from thecontrolled area, then the marker thereof can be deactivated and/ordetached therefrom. Consequently, the article can be carried through thesurveillance zone without being detected by the monitoring system and/orwithout triggering the alarm. In contrast, if an article enters thesurveillance zone with an active marker, then an alarm may be triggeredto indicate possible unauthorized removal thereof from the controlledarea.

In acoustomagnetic or magnetomechanical based EAS systems, themonitoring system excites the marker by transmitting an electromagneticburst at a resonance frequency of the marker. When the marker is presentwithin the electromagnetic field created by the transmission burst, themarker begins to resonate with an acoustomagnetic or magnetomechanicalresponse frequency that is detectable by a receiver in the monitoringsystem. The monitoring system may then trigger the alarm.

Notably, the resonance frequency and response frequency are the same.The waveform of the monitoring system's transmitter and the intendedreceiver signal are the same as well. As a result, if a distanttransmitter of a remote EAS system is not phased properly relative tothe local EAS system, the remote EAS system could transmit atransmission burst during a receiver timeslot of the local EAS system.Accordingly, pulsed EAS systems are required to be phased togetherbecause the transmit and receive signals can be misinterpreted by theEAS systems if not timed properly. Phasing is a complex issue. If notdone properly, EAS systems will be desensitized or possibly false alarm.Conventional solutions have been focused on auto phasing schemes, whichhave either tried to align transmitters or find “quiet” locations intime versus the environment.

SUMMARY

The present invention concerns implementing systems and methods fordetecting a marker in a pulsed EAS system (e.g., a magnetic based EASdetection system). The methods comprise transmitting, from an EASdetection system, an excitation signal having a first frequency into aninterrogation zone during a transmit phase of the EAS detection system.The excitation signal causes the marker to transmit a response signalhaving a second frequency different from the first frequency. Theresponse signal is received at the EAS detection system during a receivephase of the EAS detection system.

In some scenarios, the first frequency has a value that cannot be or isunable to be detected by a receiver of the second frequency. The secondfrequency can be less than or greater than the first frequency. Thesecurity tag may comprise a first coil, a second coil, a core on whichthe first and second coils are disposed, and a timing circuitelectrically coupled to the first and second coils.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described with reference to the following drawingfigures, in which like numerals represent like items throughout thefigures.

FIG. 1 is an illustration of an illustrative system.

FIGS. 2 and 3 provide illustrations of an illustrative EAS detectionsystem.

FIG. 4 is an illustration of an illustrative system controller for anEAS detection system.

FIG. 5 is an illustration of an illustrative marker architecture.

FIG. 6 is an illustration of another illustrative marker architecture.

FIG. 7 is a flow diagram of an illustrative method for detecting amarker in an EAS system.

DETAILED DESCRIPTION

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the appended figures couldbe arranged and designed in a wide variety of different configurations.Thus, the following more detailed description of various embodiments, asrepresented in the figures, is not intended to limit the scope of thepresent disclosure, but is merely representative of various embodiments.While the various aspects of the embodiments are presented in drawings,the drawings are not necessarily drawn to scale unless specificallyindicated.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by this detailed description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussions of the features and advantages, and similar language,throughout the specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize, in light ofthe description herein, that the invention can be practiced without oneor more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments of the invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or similar language means that a particular feature,structure, or characteristic described in connection with the indicatedembodiment is included in at least one embodiment of the presentinvention. Thus, the phrases “in one embodiment”, “in an embodiment”,and similar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

As used in this document, the singular form “a”, “an”, and “the” includeplural references unless the context clearly dictates otherwise. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meanings as commonly understood by one of ordinary skill in theart. As used in this document, the term “comprising” means “including,but not limited to”.

The present solution relates to EAS systems absent of a phasingrequirement. Since there is no longer a phasing requirement, the EASsystems are able to be setup without assistance. The EAS systems aredesigned so that at least one signal characteristic of the transmit andreceive signals is the same. The signal characteristic includes, but isnot limited to, a frequency. For example, in some scenarios, theresonance frequency F₁ and response frequency F₂ are different (i.e.,F₁≠F₂). In effect, the marker (e.g., security tag or label) cannot beexcited by a far field transmitter of another EAS system. As such, theremote transmitter in any position (time—relative to the zero crossingof an AC line) will not corrupt the marker's interrogation of the localEAS system. Therefore, false alarms are at least significantly reducedby the present solution.

Referring now to FIG. 1, there is provided an illustration of anillustrative system 100. System 100 comprises a plurality of EASdetection systems 104 a, 104 b, 104 c. Each of the EAS detection systems104 a, 104 b, 104 c is configured to monitor an area 102 a, 102 b, 102 c(e.g., within a certain range of the EAS detection systems) as is knownto detect EAS markers 106 having a predetermined characteristic (e.g.,frequency). The coverage for each area 102 a, 102 b, 102 c may overlapwith adjacent areas. Further, the EAS detection systems 104 a, 104 b,104 c may be configured to communicate information therebetween usingany suitable communications links (e.g., a wireless communicationslink).

Referring now to FIGS. 2 and 3, there are provided illustrations of anillustrative EAS detection system 200. EAS detection system 104 a, 104b, 104 c of FIG. 1 is the same as or similar to EAS detection system 200of FIG. 2. As such, the following discussion of EAS detection system 200is sufficient for understanding EAS detection systems 104 a, 104 b, 104c of FIG. 1. EAS detection system 200 is described herein in terms of anAM EAS type detection system. However, the present solution can also beused in other types of EAS detection systems, including other types ofmagnetic based EAS detection systems.

The EAS detection system 200 will be positioned at a location adjacentto an entry/exit 204 of a secured facility (e.g., a retail store). TheEAS detection system 200 uses specially designed EAS markers 302 whichare applied to store merchandise or other items which are stored withina secured facility. The EAS markers 302 can be deactivated or removed byauthorized personnel at the secure facility. For example, in a retailenvironment, the EAS markers 302 could be removed by a store employee(not shown). When an active EAS marker 302 is detected by the EASdetection system 200 in an idealized representation of an EAS detectionzone 300 near the entry/exit, the EAS detection system 200 will detectthe presence of such marker 302 and will sound an alarm or generate someother suitable EAS response, as described above. Accordingly, the EASdetection system 200 is arranged for detecting and preventing theunauthorized removal of articles or products from controlled areas.

The EAS detection system 200 includes a pair of pedestals 202 a, 202 b,which are located a known distance apart (e.g., at opposing sides of anentry/exit 204). The pedestals 202 a, 202 b are typically stabilized andsupported by a base 206 a, 206 b. The pedestals 202 a, 202 b will eachgenerally include one or more antennas 108 that are suitable for aidingin the detection of the special markers, as described herein. Forexample, pedestal 202 a can include at least one antenna suitable fortransmitting or producing an electromagnetic exciter signal field andreceiving response signals generated by markers in the EAS detectionzone 300. In some scenarios, the same antenna 208 can be used for bothreceive and transmit functions. Similarly, pedestal 202 b can include atleast one antenna 208 suitable for transmitting or producing anelectromagnetic exciter signal field and receiving response signalsgenerated by markers in the EAS detection zone 300. The antennasprovided in pedestals 202 a, 202 b can be conventional conductive wirecoil or loop designs as are commonly used in AM type EAS pedestals.These antennas will sometimes be referred to herein as exciter coils. Insome scenarios, a single antenna can be used in each pedestal. Thesingle antenna is selectively coupled to the EAS receiver. The EAStransmitter is operated in a time multiplexed manner. However, it can beadvantageous to include two antennas (or exciter coils) in each pedestalas shown in FIG. 1, with an upper antenna positioned above a lowerantenna.

The antennas 208 located in the pedestals 202 a, 202 b are electricallycoupled to a system controller 210. The system controller 210 controlsthe operation of the EAS detection system 202 to perform EAS functionsas described herein. The system controller 210 can be located within abase 206 a, 206 b of one of the pedestals 202 a, 202 b or can be locatedwithin a separate chassis at a location nearby to the pedestals. Forexample, the system controller 210 can be located in a ceiling justabove or adjacent to the pedestals 202 a, 202 b.

As noted above, the EAS detection system comprises an AM type EASdetection system. As such, each antenna is used to generate anElectro-Magnetic (“EM”) field which serves as a marker exciter signal(or interrogation signal). The marker exciter signal causes a responsesignal to be generated by the marker within an EAS detection zone 300.In some scenarios, the marker comprises a plurality of resonators havingdifferent lengths which facilitate the reception of the marker excitersignal having a first frequency and the generation of a response signalhaving a second different frequency. In other scenarios, the markercomprises two coils with a common core (e.g., a ferrite core). Thepresent solution is not limited to the marker architectures of these twoscenarios. Other marker architectures can be used herein.

An illustration of an illustrative marker 500 is provided in FIG. 5. Asshown in FIG. 5, the marker 500 comprises a plurality of resonators 502with different lengths. The marker also comprises an optional spacer 504and a bias element 506. Components 502-506 are well known in the art,and therefore will not be described herein.

An illustration of an illustrative marker 600 with a common core 602architecture is shown in FIG. 6. During operation, the marker excitersignal causes a first voltage V1 to be generated by a first coil 604contained in the marker's housing 610. The first voltage V1 is suppliedto a timing circuit 608 also contained in the marker's housing 610. Someor all components of the timing circuit 608 can be implemented ashardware, software and/or a combination of hardware and software. Thehardware includes, but is not limited to, one or more electroniccircuits. The electronic circuits can include, but are not limited to,passive components (e.g., resistors and capacitors) and/or activecomponents (e.g., amplifiers and/or microprocessors). The passive and/oractive components can be adapted to, arranged to and/or programmed toperform one or more of the methodologies, procedures, or functionsdescribed herein. Upon the expiration of a pre-defined amount of time,the timing circuit 608 supplies a second voltage V2 to a second coil606. The second voltage V2 can be the same as or different than thefirst voltage V1. In turn, the second coil 606 emits a response signaltherefrom. The response signal has a frequency that is different thanthe frequency of the marker exciter signal.

The response signal transmission will continue for a brief time afterthe stimulus signal is terminated. The response signal is received atthe receiver antenna. The received response signal is used to indicate apresence of the marker within the EAS detection zone. As noted above,the same antenna contained in a pedestal 202 a, 202 b can serve as boththe transmit antenna and the receive antenna. Accordingly, the antennasin each of the pedestals 202 a, 202 b can be used in several differentmodes to detect a marker exciter signal.

Referring now to FIG. 4, there is provided an illustration ofillustrative architecture for the system controller 210 of FIG. 2. Thesystem controller 210 comprises a power amplifier 406, a transmittercircuit 408, a receiver circuit 412, and a processor 410. Each of thelisted components are well known in the art, and therefore will not bedescribed in detail herein.

As shown in FIG. 4, the transmitter circuit 408 is coupled to a firstantenna 208 a, and the receiver circuit 412 is coupled to a secondantenna 208 b. The first antenna 208 a may be disposed in a firstpedestal 202 a of a pair of pedestals, and the second antenna 208 b forthe receiver circuit 412 may be disposed in a second pedestal 202 b ofthe pair of pedestals. The present solution is not limited in thisregard. For example, both antennas 208 a and 208 b can be contained inthe same pedestal, and/or collectively comprise a single antenna.

The listed components 406-412 together define a marker monitoringcontrol portion that controls the transmission from and reception ofsignals at an antenna 208 a, 208 b. The marker monitoring controlportion can be provided in any known manner to control the transmissionsand receptions at the interrogation antenna 402 to monitor for EASmarkers 302 within an interrogation zone 300. The system controller 210also includes an optional communication antenna 414 and an optionaltransceiver 416 to provide communications between different controllersin one or more EAS detection systems.

The operations of the marker monitoring control portion will now bedescribed in more detail. The transmitter circuit 408 is coupled to thefirst antenna 208 a via the power amplifier 406. The first antenna 208 aemits transmit (e.g., “Radio Frequency (“RF”)) bursts at a predeterminedfrequency (e.g., 58 KHz) and a repetition rate (e.g., 50 Hz, 60 Hz, 75Hz or 90 Hz), with a pause between successive bursts. In some scenarios,each transmit burst has a duration of about 1.6 ms. The transmittercircuit 408 is controlled to emit the aforementioned transmit bursts bythe processor 410, which also controls the receiver circuit 412. Thereceiver circuit 412 is coupled to the second antenna 208 b. The secondantenna 208 b comprises close-coupled pick up coils of N turns (e.g.,100 turns), where N is any number.

When the EAS marker 302 resides between the antennas 208 a, 208 b asshown in FIG. 3, the transmit bursts transmitted from the transmittercircuit 408 cause a response signal to be generated by the EAS marker302. Notably, the frequency F₂ of the response signal is different thanthe frequency F₁ of the transmit bursts, i.e., F₁≠F₂. The frequencies F₁and F₂ have values selected so that cross-talk will not occur and/or sothat interference does not occur between the two signals. In thisregard, the frequency F₁ has to be such that it cannot be or is unableto be seen by the receiver of frequency F₂. This will be dictated by thetypical bandwidth of the receiver. For example, in some scenarios, adifference between the values of the frequencies F₁ and F₂ is at least3-5 KHz. The second frequency F₂ can be greater than or less than thefirst frequency F₁. Thus, if the first frequency F₁ is 58 KHz, then thesecond frequency F₂ is 53 KHz or 63 KHz. The present solution is notlimited to the particulars of this example.

The processor 410 controls activation and deactivation of the receivercircuit 412. When the receiver circuit 412 is activated, it detectssignals at the predetermined frequency (e.g., 53 KHz or 63 KHz) withinfirst and second detection windows. In the case that a transmit bursthas a duration of about 1.6 ms, the first detection window will have aduration of about 1.7 ms which begins at approximately 0.4 ms after theend of the transmit burst. During the first detection window, thereceiver circuit 412 integrates any signal at the predeterminedfrequency which is present. In order to produce an integration result inthe first detection window which can be readily compared with theintegrated signal from the second detection window, the signal emittedby the EAS marker 302 should have a relatively high amplitude (e.g.,greater than or equal to about 1.5 nanowebers (nWb)).

After signal detection in the first detection window, the processor 410deactivates the receiver circuit 412, and then re-activates the receivercircuit 412 during the second detection window which begins atapproximately 6 ms after the end of the aforementioned transmit burst.During the second detection window, the receiver circuit 412 again looksfor a signal having a suitable amplitude at the predetermined frequency(e.g., 53 kHz or 63 KHz). Since it is known that a signal emanating fromthe EAS marker 302 will have a decaying amplitude, the receiver circuit412 compares the amplitude of any signal detected at the predeterminedfrequency during the second detection window with the amplitude of thesignal detected during the first detection window. If the amplitudedifferential is consistent with that of an exponentially decayingsignal, it is assumed that the signal did, in fact, emanate from an EASmarker 302 between antennas 208 a, 208 b. In this case, the receivercircuit 412 issues an alarm.

Referring now to FIG. 7, there is provided a flow diagram of anillustrative method 700 for detecting a marker (e.g., marker 500 of FIG.5 or marker 600 of FIG. 6) in an EAS system (e.g., system 100 of FIG.1). Method 700 begins with 702 and continues with 704 where anexcitation signal is transmitted from an EAS detection system (e.g., EASdetection system 104 a-104 c of FIG. 1 or EAS detection system 200 ofFIG. 2) into an interrogation zone (e.g., interrogation zone 300 of FIG.3) during a transmit phase of the EAS detection system. The excitationsignal has a first frequency F1. The excitation signal is then receivedby the marker located in the interrogation zone, as shown by 706. Inresponse to the excitation signal, the marker generates a responsesignal in 708. The response signal has a second frequency F2 differentfrom the first frequency F1. The second frequency can be less than orgreater than the first frequency. Next in 710, the response signal istransmitted from the marker. The response signal is received at the EASdetection system during a receive phase of the EAS detection system, asshown by 712. Subsequently, 714 is performed where method 700 ends orother processing is performed (e.g., return to 704).

Although the invention has been illustrated and described with respectto one or more implementations, equivalent alterations and modificationswill occur to others skilled in the art upon the reading andunderstanding of this specification and the annexed drawings. Inaddition, while a particular feature of the invention may have beendisclosed with respect to only one of several implementations, suchfeature may be combined with one or more other features of the otherimplementations as may be desired and advantageous for any given orparticular application. Thus, the breadth and scope of the presentinvention should not be limited by any of the above describedembodiments. Rather, the scope of the invention should be defined inaccordance with the following claims and their equivalents.

What is claimed is:
 1. A method for detecting a marker in a pulsedElectronic Article Surveillance (“EAS”) system, comprising:transmitting, from an EAS detection system, an excitation signal havinga first frequency into an interrogation zone during a transmit phase ofthe EAS detection system, the excitation signal causing the marker totransmit a response signal having a second frequency different from thefirst frequency; and receiving the response signal at the EAS detectionsystem during a receive phase of the EAS detection system.
 2. The methodaccording to claim 1, wherein the first frequency has a value that isunable to be detected by a receiver of the EA second frequency.
 3. Themethod according to claim 1, wherein the second frequency is less thanthe first frequency.
 4. The method according to claim 1, wherein thesecond frequency is greater than the first frequency.
 5. The methodaccording to claim 1, wherein the EAS detection system comprises amagnetic based EAS detection system.
 6. The method according to claim 1,wherein the marker comprises a first coil, a second coil, a core onwhich the first and second coils are disposed, and a timing circuitelectrically coupled to the first and second coils.
 7. A method foroperating an Electronic Article Surveillance (“EAS”) system, comprising:transmitting, from an EAS detection system, an excitation signal havinga first frequency into an interrogation zone during a transmit phase ofthe EAS detection system; receiving the excitation signal at a markerlocated within the interrogation zone; generating, by the marker, aresponse signal in response to the excitation signal, the responsesignal having a second frequency different from the first frequency;transmitting the response signal from the marker; and receiving theresponse signal at the EAS detection system during a receive phase ofthe EAS detection system.
 8. The method according to claim 7, whereinthe first frequency has a value that is unable to be detected by areceiver of the second frequency.
 9. The method according to claim 7,wherein the second frequency is less than the first frequency.
 10. Themethod according to claim 7, wherein the second frequency is greaterthan the first frequency.
 11. The method according to claim 7, whereinthe EAS detection system comprises a magnetic based EAS detectionsystem.
 12. The method according to claim 7, wherein the markercomprises a first coil, a second coil, a core on which the first andsecond coils are disposed, and a timing circuit electrically coupled tothe first and second coils.
 13. A pulsed Electronic Article Surveillance(“EAS”) system, comprising: a marker; and an EAS detection systemcomprising a circuit configured to transmit an excitation signal havinga first frequency into an interrogation zone during a transmit phase ofthe EAS detection system, the excitation signal causing the marker totransmit a response signal having a second frequency different from thefirst frequency, and receive the response signal during a receive phaseof the EAS detection system.
 14. The pulsed EAS system according toclaim 1, wherein the first frequency has a value that is unable to bedetected by the second frequency.
 15. The pulsed EAS system according toclaim 1, wherein the second frequency is less than the first frequency.16. The pulsed EAS system according to claim 1, wherein the secondfrequency is greater than the first frequency.
 17. The pulsed EAS systemaccording to claim 1, wherein the EAS detection system comprises amagnetic based EAS detection system.
 18. The pulsed EAS system accordingto claim 1, wherein the marker comprises a first coil, a second coil, acore on which the first and second coils are disposed, and a timingcircuit electrically coupled to the first and second coils.